Musical instrument sound generating system with feedback

Abstract

A system for remotely generating sound from a musical instrument includes a calibration system to improve the quality of the sound produced by the musical instrument. In one embodiment, the system includes an input configured to receive a signal representative of the sound of a first musical instrument, an exciter for converting the signal to mechanical vibrations, a coupling interface for coupling the mechanical vibrations into a second musical instrument, and a calibration system for altering the signal sent to the exciter.

I claim: 
     
       1. A system for attaching to an unmodified acoustic instrument, the system comprising:
 an input configured to receive an externally generated signal representative of sound of a first musical instrument; 
 at least one exciter configured to convert an electrical signal to mechanical vibrations; 
 at least one coupling interface configured to couple the mechanical vibrations to a previously unmodified acoustic instrument such that the previously unmodified acoustic instrument generates audible sounds in response to the mechanical vibrations; 
 a calibration system configured to measure an output response of the previously unmodified acoustic instrument, compare the output response to a target response, generate an error signal, create a modified version of the externally generated signal based on the error signal, and present the modified version of the externally generated signal as an electrical signal to the at least one exciter and wherein the calibration system comprises a digital signal processor and at least a mechanical or acoustic transducer to measure the output response of the previously unmodified acoustic instrument and wherein the digital signal processor is configured to generate a calibration signal for application to the input, receive a first feedback signal representing the audible sounds, compare the first feedback signal to an expected response, and generate a corrective transfer function; and 
 wherein the externally generated signal is routed to a processing block which modifies the externally generated signal by the corrective transfer function. 
 
     
     
       2. The system of  claim 1  further comprising a housing, wherein the digital signal processor and at least a portion of the input are contained within the housing. 
     
     
       3. The system of  claim 1  further comprising a housing, wherein the housing is configured to be mounted to the previously unmodified acoustic instrument. 
     
     
       4. The system of  claim 3  wherein at least a first exciter contacts at least a portion of the previously unmodified acoustic instrument when the housing is mounted to the previously unmodified acoustic instrument. 
     
     
       5. The system of  claim 1  comprising a mechanical transducer and an acoustic transducer; wherein the mechanical transducer is arranged to output a mechanical feedback signal which is compared to a mechanical transfer function to generate a mechanical error signal and the acoustic transducer is arranged to generate an acoustic feedback signal which is compared to an acoustic transfer function to generate an acoustic error signal, wherein the mechanical error signal and the acoustic error signal are analyzed by the digital signal processor to create the corrective transfer function. 
     
     
       6. An apparatus comprising:
 an input configured to selectively receive an externally generated signal from a first musical instrument or an internally generated calibration signal; 
 a transducer configured to produce a feedback signal in response to vibrations of a second musical instrument, wherein the vibrations of the second musical instrument are created by an exciter coupled to the second musical instrument; 
 at least a first processing block arranged between the input and the exciter, the first processing block configured to apply a transfer function to at least the externally generated signal, thereby creating an output signal which is an altered version of the externally generated signal and wherein the output signal is sent to the exciter, causing the vibrations of the second musical instrument to be altered; 
 and wherein the transfer function changes in response to the feedback signal produced by the transducer. 
 
     
     
       7. The apparatus of  claim 6  wherein the internally generated calibration signal is generated by a digital signal processor and wherein the feedback signal is provided as an input to the digital signal processor. 
     
     
       8. The apparatus of  claim 6  wherein the transducer is a mechanical transducer configured to produce the feedback signal in response to vibrations in a body of the second musical instrument. 
     
     
       9. The apparatus of  claim 6  wherein the transducer is an acoustic transducer configured to produce the feedback signal in response to an acoustic output of the second musical instrument. 
     
     
       10. The apparatus of  claim 8  further comprising an acoustic transducer configured to produce an acoustic feedback signal in response to an acoustic output of the second musical instrument. 
     
     
       11. A system for mounting to an acoustic guitar, the system comprising:
 an input for receiving an externally generated signal representative of sound of a first musical instrument; 
 at least one processing block configured to modify the externally generated signal according to a transfer function to create a corrected output; 
 at least one exciter for creating vibrations in the acoustic guitar in response to the corrected output, the vibrations producing sounds from the acoustic guitar; 
 and 
 at least one transducer configured to produce a feedback signal in response to the vibrations or sounds from the acoustic guitar, wherein the transfer function is altered in response to the feedback signal to create a corrective transfer function, resulting in a corrected output comprising the externally generated signal modified by the corrective transfer function. 
 
     
     
       12. The system of  claim 11 , wherein at least a first of the at least one transducer is mechanically coupled to the acoustic guitar when the system is mounted to the acoustic guitar. 
     
     
       13. The system of  claim 11  further comprising a switching means for selecting between the externally generated signal and a calibration signal. 
     
     
       14. The system of  claim 11  further comprising a calibration system configured to send a calibration signal to the at least one exciter and wherein the calibration system modifies at least a portion of the corrective transfer function in response to the feedback signal. 
     
     
       15. The system of  claim 14  wherein the calibration system further comprises a signal generator configured to generate the calibration signal. 
     
     
       16. The system of  claim 14  wherein the calibration system includes at least a mechanical target response signal or at least an acoustic target response signal. 
     
     
       17. The apparatus of  claim 6 , wherein the transfer function is applied to the internally generated calibration signal.